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SPIKE:
improved software
for the Signal Hound
By JIM ROWE
When we reviewed the Signal Hound USB-SA44B mini
spectrum analyser in the October 2014 issue of SILICON CHIP, we were
very impressed with the performance of both the hardware and its accompanying
software. Now Signal Hound has come up with a greatly enhanced software pack
age to go with the USB-SA44B and their other instruments.
I
N OUR ORIGINAL review of the
USB-SA44B spectrum analyser, we
were particularly impressed with the
analyser hardware itself. Inside its
compact 77 x 27 x 167mm aluminium
case there is an advanced narrow-band
SDR receiving system tuning over
the range from 1Hz to 4.4GHz and
delivering a level of performance that
compares very favourably with high-
end self-contained spectrum analysers
– but at a fraction of their price.
We were also impressed with its
software package which controls the
USB-SA44B hardware box (and the optional USB-TG44A tracking generator)
from your PC as well as accepting, processing and analysing the output data
stream from it to produce the analyser’s
output display and measurements.
Fig.1: a full-screen grab of Spike in “real time” mode scanning at a centre frequency of 1090MHz, showing Persistence on the spectrum plot (lower centre), with
a 2D spectrogram above it.
78 Silicon Chip
The software did have a few rough
edges but we judged them to be fairly
minor and not significant, considering
the excellent performance of the USBSA44B hardware. But early this year
Signal Hound released a greatly enhanced version of their software package, renamed “Spike”. And in the last
three months or so they’ve released a
number of upgraded versions of Spike.
We’re reviewing the latest version
at the time of writing: Spike 3.06.
This is now being provided on the
CD accompanying the USB-SA44B
and other analysers purchased new.
Existing users can download it at no
charge from Signal Hound’s website at
www.signalhound.com/spike
It comes as a zip file which includes
its matching USB drivers. A PDF of
the User Manual for the new software
can also be downloaded from the same
website.
Spike 3.06 is compatible not just
with the USB-SA44B but also with
the rest of the Signal Hound products,
including the USB-TG44A tracking
generator. There are two versions,
compatible with the 32-bit or 64-bit
versions of either Windows 7, 8 or 8.1.
Note that although the Spike softsiliconchip.com.au
Fig.2: a spectrum plot showing the Sydney DRMT DAB+
signal block centred on 204.5MHz in channel 9A, captured
using Spike 3.06 and saved as a JPEG file.
Fig.3: another plot centred on 92.9MHz, showing the Sydney ABCFM signal spectrum (bottom) with a 2D spectrogram above it. Spike again saved it as a JPEG file.
ware can be downloaded and installed
at no charge, it will only work with
Signal Hound devices like the USBSA44B. When you start up the software
it automatically searches the PC’s USB
ports to see if one or more of the devices is connected. When it finds one,
it displays the device’s serial number
and other information (like internal
temperature and firmware revision) at
bottom right on its main display window; otherwise it refuses to proceed.
What’s new?
The first thing you notice when you
fire up Spike (in my case, with a USBSA44B) is that the user interface window has been completely revamped.
The main display graticule is now
centred on the screen, with control
panel menus running down either
side. It’s less crowded than before,
having been proportioned to suit the
16x9 wide-screen aspect ratio used on
most modern laptops and PC monitors.
As before, the main functions, settings and facilities are selected using
a menu bar and toolbar running along
the top. The control panel menus on
the left side then allow you to set the
Measurement trace and marker parameters, any offsets that may be required
and settings for Channel Power and
Occupied Bandwidth measurements.
The menus on the right side control
panel allow easy setting of all sweep
parameters: Frequency (Centre, Span,
Start, Stop and Step, plus the ability
to set the analyser for either Full Span
or Zero Span [more about this later]);
siliconchip.com.au
Fig.4: this full-screen grab shows Spike 3.06 in real-time scanning mode, centred
at 1090MHz (the frequency used by commercial aircraft for ADSB). The 2-D
spectrogram is shown above the spectrum plot itself.
Amplitude (Reference Level and Graticule Divisions, plus the ability to select
either manual or automatic internal
gain, attenuation and preamp enabling); Bandwidth (RBW and VBW);
and finally Acquisition options such
as Video units, Detector mode and
Sweep Time.
This is not Spike’s only display
graticule or control menu panel, as
will become clear shortly. So Spike’s
initial window is much snazzier than
that of the original Signal Hound software. But that’s only the start of its new
features and capabilities, because
the new software can now take full
advantage of the capabilities of Signal
Hound’s analyser hardware – including those of the USB-SA44B.
For example, you can now select
either of two different types of spectrogram to accompany the analyser’s
main amplitude vs frequency display:
a 2D spectrogram which gives the moving “waterfall” display or a 3D spectrogram which gives a series of sweep
displays receding into the distance.
These can both be helpful when you’re
trying to look for significant events.
Another nice new feature applying
to the main graticule display is persistence. When you enable this feature,
the current signal trace is accompanied
by a “community” of earlier traces, in
colours representing their time prior
to the current trace.
It’s a bit like having a fixed spectrogram displayed directly behind the
June 2015 79
Fig.5: another screen grab showing Spike in real-time scanning mode, centred at
1090MHz, this time with a 3-D spectrogram shown above the spectrum plot.
Fig.6: this screen grab shows Spike 3.06 in “zero span” mode – another of its
exciting new features, designed to facilitate modulation analysis. It shows the
actual spectrum plot at lower left, with the modulation plotted against time at
upper left and the I/Q IF output stream at lower centre. A summary of the signal
and modulation data is shown at upper centre.
trace itself, in the main graticule.
There’s another new feature that’s
even more impressive: Spike now
provides a real-time spectrum analysis
mode, to allow capturing occasional
short-term events which can easily
be missed in normal sweep analysis
if they occur during the “dead time”
between sweeps.
In real-time analysis mode, Spike
takes advantage of the ability of Spectrum Hound’s analyser hardware to
stream its full IF bandwidth back to
the PC (via the USB cable) continuously, with no time gaps. So by limiting the sweep span to the maximum
instantaneous bandwidth, Spike is
now able to process and analyse every
spectrum sample in real time.
Incidentally, the spectrogram and
80 Silicon Chip
persistence features can be applied
in real-time mode just as easily as
in sweep mode. If this isn’t enough,
there’s now a zero-span analysis mode
too. This might sound a bit strange but
it’s really quite easy to understand.
In zero span mode, Spike directs the
analyser to stay locked to the centre
frequency you’ve set, while it again
streams the full IF bandwidth back
to the PC.
This allows Spike to demodulate
any AM, FM or PM modulation
which may be present on a signal
at that centre frequency. As a result,
when Spike is in zero-span mode, the
screen changes dramatically, with the
RF amplitude vs frequency spectrum
graticule reduced in size and moved
to the lower left, while the modulation
is displayed plotted against time in a
new graticule across the top.
In addition, the I and Q components of the analyser’s IF data stream
are displayed in a third graticule at
lower right, alongside the amplitude
vs frequency plot. Then if you enable
Spike’s AM/FM modulation analysis
feature, the upper modulation vs time
graticule contracts to the left, and quite
a bit of modulation analysis data is
displayed in the top right quadrant.
You’re shown a continuously updated summary of RMS, Peak+ and
Peak- modulation percentages, plus
the modulation frequency and RF centre frequency, together with the SINAD
(dB) and THD (%) figures.
Other features
There are other noteworthy features
as well, including:
(1) The ability to call up an Audio
Player function, to listen to any AM or
FM modulation of the centre frequency
signal via the PC’s speakers;
(2) The ability to call up a Measuring
Receiver function, to display various
key parameters of the centre frequency
signal;
(3) The ability to record the data from
an analyser session as a file on the PC,
and also to replay a recorded file for
further analysis;
(4) In zero-span mode, there’s also
the ability to save a short duration
I/Q capture, either as a binary file or
in a text-based format such as a CSV
(comma separated variable) file;
(5) The ability to plot phase noise and
(6) If you add a USB-TG44A Tracking
Generator to your set-up, the software
can be easily set up to perform scalar
network analysis.
In short, Signal Hound’s new Spike
3.06 software really expands the
measurement applications of their
USB-based spectrum analysers (like
the USB-SA44B) dramatically, as well
as taking full advantage of the hithertohidden performance features of the
analyser hardware.
The new User Manual for Spike is
also a significant improvement on the
original manual, which was already
pretty good.
In Australia and New Zealand,
Signal Hound products like the
USB-SA44B and the USB-TG44A are
distributed by Silvertone Electronics,
now based in Wagga Wagga, NSW.
You’ll find their website: www.silverSC
tone.com.au
siliconchip.com.au
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